Abstract: The application of infrared thermography technology to microwave multi-chip mod ule(MMCM) is discussed in this paper. Especially, the thermal design of packagin g and interconnecting of microwave high power amplifier chip, the control of ov er-heated point for modulation chip and diagnostic technique of small signal am plifier chip are described. According to the analysis of infrared imaging, the thermal design of MMCM is improved, and excellent result is achieved. It is show n that infrared thermography technology is a powerful instrument for improving t he reliability of MMCM.